The Long-Running Mystery of the World Hum Still Has No Clear Answer

For decades, thousands of people around the world have reported hearing a low, continuous humming sound that others around them cannot detect. The phenomenon, known as the “world hum,” remains unexplained despite multiple scientific studies, and it continues to puzzle researchers.

The first reports surfaced in Bristol, England, in the 1970s, when local newspapers received letters from residents describing an unending low noise. Similar complaints later came from across Britain, Europe, North America, Australia and New Zealand, suggesting the phenomenon was not confined to one country.

One of the best-known cases came in 1993 in Taos, New Mexico, after a local woman told a newspaper that the hum was ruining her life and keeping her from sleeping. Other residents then said they heard it too. A classic description compares it to an idling car or truck engine, louder at night and indoors, and easier to hide under background noise.

The Taos reports prompted a public investigation, with a local congressman bringing in scientists from Air Force laboratories, Los Alamos, Sandia and a nearby university. They used advanced equipment, but the source remained unresolved. In 2012, the “Worldwide Hum Project” website was launched so people could report hearing it. Research led by Professor Marcus Drexler of the Norwegian University of Science and Technology examined 28 hum listeners, but did not support theories that they simply hear low frequencies better or that the sound comes from the inner ear. Drexler said the most convincing explanation is that the hum is a unique form of tinnitus, though researchers believe there are probably several different causes, which may explain why some people hear it constantly and others only in certain places or at certain times.